The bicycle market, particularly in the United States and Europe, has been growing steadily. As the population adopts a healthier and fitness conscious lifestyle, many have turned to bicycling as part of their fitness regimen. Additionally, rising fuel costs, increased congestion on roads, lack of parking availability as well as the increased focus on eco-friendly means of transportation in order to curb pollution, have made bicycles the emerging alternatives for shorter distance transportation. Moreover, regulatory initiatives to promote cycling in order to reduce harmful carbon emissions and noise pollution have purred bicycle industry growth.
In major cities where living and working space is at a premium, the downside of a traditional bicycle is its large footprint, so there has been an increased demand for folding bicycles that have a smaller footprint. The compact nature of a folding bicycle, allows it to be stored out of the way, in unused corners of an office or in an apartment closet, when not in use. Additionally, folding bicycles are ideal for commuting, where a person can ride to a train or subway, fold the bicycle to bring on the train, and then finishing the commute by unfolding the bike and riding to the office.
However, because folding bicycles need to maintain a strong frame due to the stresses put on the frame while riding, the majority of folding bicycles maintain the traditional diamond frame configuration, which is made of two triangles; a main triangle and a paired rear triangle.
The diamond frame construction makes it extremely difficult to fold a bicycle on the longitudinal axis as a vertical fold would require more than one folding point. As well, bicycles are in line from the front wheel assembly to the back wheel, so a vertical fold will result in the front and rear wheels coming into contact, limiting the folding range. Folding frames instead use a horizontal hinge point (with single or double hinges) allowing the bicycle to fold approximately in half along a horizontal axis.
Other types of folding bicycles, such as the triangle hinge style, allow the rear triangle and wheel to be folded down and flipped forward, under the main frame tube. Some of these types may also have a secondary folding hinge at the front fork assembly.
An additional problem with many folding bicycles is that although compact when folded, moving them while folded requires that they be carried. To make carrying the bicycles easier, most tend to use smaller wheels, which makes the folded bike easier to carry but also hampers the riding experience.